ONAFTERPRINT 事件在错误的按钮上触发

Question

I need to know if the user has click the print or cancel button but onafterprint event fires if either was clicked, why ??

window.onafterprint = () => {

    // event should fire only if print button is clicked

}

Enter this page and do the Ctrl + p try to cancel or print or save the document and watch the alert

can anyone please explain ?

Answer 1

The afterprint event is fired after the associated document has started printing or the print preview has been closed. MDN

It seems that you can't know through the event. The specification does not tell user agents to distinguish between printing or canceling the print prompt. Although the spec is quite vague about what to actually do. WHATWG Spec .

Answer 2

The onafterprint event occurs when a page has started printing, or if the print dialogue box has been closed. That's why the event fires with both buttons.

So, there's no way to know if the user clicked Save or Cancel.